1. Field of the Invention
This invention relates, in general, to a method for design and manufacture of closures and dispensing components for packaging of consumer goods and in particular packaging components incorporating removable membranes to form a primary seal.
2. Description of Related Art
Tamper-evidencing closure systems are known and often include a closure having a removable tamper-evidencing portion that is monolithically formed with the remainder of the closure. Upon initial opening of such known closures the tamper-evidencing portion fractures and/or tears away from the remainder of the closure.
One known type of closure system utilizes a cap having a skirt and a tamper-evident band dependent from and monolithically joined to a base of the skirt. The band is engaged with complimentary structure on a corresponding container and is severed from the cap skirt when the closure is initially removed. The severing is allowed by making the interconnection between the tamper-evident band and the cap skirt frangible and easily broken. Typically, discrete breakable “bridges” or a continuous thin “score line” is utilized to form the frangible connection.
One exemplar of the prior art is U.S. Pat. No. 5,480,045 to Molinaro et al. which discloses a cap including a frangible tear skirt interconnected with a depending wall by frangible connection members. Another exemplar of the prior art is U.S. Pat. No. 5,284,265 to Crisci which discloses a cap having a frangible tear skirt interconnected with a cap top along a score line or tear line.
Another known closure system involves monolithically molded pull-out membranes, as commonly employed on gable-top juice containers and some vegetable oil containers. This system incorporates a removable membrane initially closing a dispensing orifice of the container. The membrane is monolithically formed with additional structure appropriate for attachment to the container such as a weld flange or a snap attachment skirt. The membrane is integrally connected to the attachment structure through a frangible line of weakness. Initial opening by a consumer is done by gripping and pulling a finger tab that is joined to the membrane whereby removing the membrane fractures the closure and tears the membrane away from the additional structure along the frangible line of weakness.
An exemplar of the prior art is U.S. Pat. No. 5,810,184 to Adams et al. which discloses a fitment having a removable membrane interconnected with a spout along a line of weakness or tear line.
While prior closure systems function quite successfully, current systems using frangible separation of integrally molded components have several disadvantages. In the case of dependent breakaway tamper-evidencing bands, the demands of application and retention of the tamper-evidencing band often conflict with the requirements of the primary closure portion. For example, when discrete bridges are employed, the mechanical characteristics required for bridge integrity during application often conflict with the mechanical characteristics appropriate for easy removal by a consumer upon opening the closure system. In the case of continuous frangible score lines or tear lines, material selection is normally restricted to forms of low density polyethylene, since this is the only commodity material exhibiting facile tear performance.
Similarly, pull-out membrane closure systems generally include a membrane, a frangible score line, and an attachment structure which are monolithically molded in a single integral shot during an injection molding operation. Such configuration significantly restricts possible material choices for forming the system. The frangible score line must easily and readily tear without excessive force. As noted above, the most applicable material in this regard is low density polyethylene. However, specifying that the frangible line be made of low density polyethylene further specifies that the membrane itself, and more importantly the attachment structure, be formed of the same low density polyethylene material. Disadvantageously, this can negatively impact potential applications, since the mechanical properties of low density polyethylene may not be appropriate to accomplish the performance required for package integrity.
A further problem intrinsic with pull out membrane technology is that substantial material flow is required across a thin frangible score line which connects the pull out membrane to the container attachment structure. This configuration may lead to unusual and unpredictable performance including, but not limited to, microscopic pin holes, lamination and difficult tearing resulting from physical properties of the material which may change as the material traverses the thin frangible score line.
A continuing demand for improved shelf life for perishable products is commonly addressed by packaging these products under aseptic conditions. This technique involves first disinfecting both the product and the packaging components intended to contain the product to eliminate any trace of microorganisms and bacteria that would contribute to accelerated product deterioration at normal room temperatures. Once accomplished, the product is packaged and sealed while maintaining sterile conditions in a sterile or clean room environment. The contained product/package only leaves the sterile environment after the package has been completely sealed against the outside environment.
There are common ways of sterilizing the actual perishable product known to the art. Regarding the packaging components, all surfaces that come into eventual contact with the perishable product must be sterilized. In the case of many commonly used plastic packaging components, such as containers and closures, high temperature sterilization is not an option, since the temperatures required may cause unacceptable distortion and weakening of the plastic material. However, alternatives exist. One common method is to thoroughly wash the plastic surfaces involved with a disinfectant sterilizing solution. A requirement of such a process is that the plastic component have no surface regions that are difficult to thoroughly contact with the disinfectant solution. This requirement sometimes restricts the ability of the packaging component designer to thoroughly exploit design principles which otherwise might be appropriate for a non-aseptic package component.
An alternative approach is to irradiate the packaging component. This approach allows more intricate or complicated packaging designs. Often the irradiation is performed to bulk packaged components. The various components of the package are then assembled, filled and sealed prior to leaving the sterile, clean room environment.
One problem with the irradiation approach is that the size of the irradiation chambers is limited. The chamber size limitation combined with a required residence time of exposure can impact and limit the practical size of the packaging component being irradiated. If the size exceeds this practical limit, the rate of component irradiation can slow packaging line speeds to unacceptable levels. In addition, since the irradiation chambers are often manually loaded with the bulk packaging components, there are practical and government mandated limits to the weight of the bulk package of packaging components that can be irradiated simultaneously. Larger, heavier components can make it difficult or impractical to use the irradiation approach to sterilization.
Thus, it is highly advantageous in the practice of aseptic packaging to attempt to minimize both the complexity and size of the packaging components actually required within the clean room environment. Of course, the container itself would normally be required to the sterilized and present within the clean filling room. However, alternatives may exist regarding the primary closure and sealing system. One common choice is to accomplish the primary package seal within the clean room environment using induction or conduction sealing of the filled container with a foil comprised of a laminate including a layer of aluminum metal. Another option may be to substitute a film of plastic laminate film material comprising a barrier layer, in which case a conduction heating could be used to effect a seal to the container opening. Such “innerseal” methods have been widely practiced and are well known in the art. In these cases sterilization of the foil or laminate is relatively straightforward since these materials are light and flat by nature. The sterile package with its primary foil or film seal can be subsequently removed from the clean room and the package completed with the application of an overcap. The overcap normally does not function as the primary aseptic seal (the function of the foil or film) but can serve the valuable function of supplying dispensing convenience and reclosure to the eventual consumer.
One problem with the foil or film “innerseals” is that the overcap or secondary closure often must be removed upon initial opening to remove the foil or film in order to utilize the contents. Numerous marketing studies have shown that the consumer, while recognizing the many values of the extended life aseptic packaging, finds the requirement for foil or film removal objectionable. Often a knife or other tool is required to effectively remove the foil, and the operation can be messy.
It has been found that consumers are highly comfortable and satisfied with packages whose initial opening consists of removing a “tear-out” membrane attached to a pull ring. Pulling on the pull ring removes a membrane sealing the pouring orifice of the package. Such a membrane feature appears on many carton type containers of products such as orange juice. The tear out membranes are somewhat resin specific in that they are normally made from low density polyethylene (LDPE). LDPE is unique in that it allows facile linear tearing along a thinned score line, as is known in the industry. Examples of the use of tear out membranes for sealing plastic bottle finishes are shown and taught in U.S. Ser. No. 10/854,925, commonly owned by the assignee of the instant invention. The embodiments of that application show application of a membrane “fitment” as the primary seal mechanism for the neck of a bottle. The exterior surface of the fitments shown there have structure to mate with structure on an additional reclosure cap intended to reseal the package after the initial opening by membrane tear out.
One may propose using the tear out membrane concept with aseptic packaging. However, the current inventors are not aware of such membranes being used on aseptic packaging. The membrane structures are often somewhat complicated in design, having structural features which may be difficult to reach or effectively contact with sterilizing solution. To be suitable for aseptic application using sterilizing solution, these inhibiting structural features must be eliminated.
Alternatively, the tear out “fitment” may be sterilized using irradiation. In this case the bulk volume and mass of the fitments must be minimized, for the reasons discussed above.
Finally, when using or contemplating a tear out membrane “fitment” for an aseptic package, the primary seal of the “fitment” to the container neck is important. Even minute ingress or egress of materials from the exterior environment can negatively impact the package performance. Thus, it may be advantageous to employ a threaded attachment of the tear out membrane “fitment” to the container neck. Threaded attachment supplies the mechanical advantage which may be required to promote adequate performance of sealing between the “fitment” and container neck.
What is needed is a new and improved tamper-evidencing closure system which overcomes the above and other disadvantages of known closure systems.
The present invention provides for various embodiments one of which may teach improvements in the design and manufacture of packaging components employing pull out membranes to achieve initial sealing and provide facile initial opening.
Another embodiment may teach improved and novel designs and manufacturing methods for producing initially joined packaging components which cannot be reassembled following separation during initial package opening.
A further embodiment may advance improved component designs suitable for the aseptic packaging of perishable products.
Yet an additional embodiment may allow aseptic packaging processing incorporating improved packaging components which can be sterilized in a practical manner by either irradiation or wet sterilization techniques.
Other embodiment and their advantages should become clear in light of the following Figures and Description of preferred embodiments.